98%
921
2 minutes
20
We investigated the gas-phase isomerism and stability of host-guest complexes formed between cucurbiturils (CB[6] and CB[7]) and three ,'-bipyridine regioisomers ( = 2, 3, and 4), focusing on how molecular geometry and charge distribution influence complex formation. Ion mobility spectrometry-mass spectrometry and collision-induced dissociation experiments, supported by density functional theory (DFT) calculations, reveal distinct inclusion and exclusion complex isomers. Singly-protonated bipyridines tend to form exclusion complexes with CB[6], while doubly-protonated forms enable stable inclusion through enhanced charge-portal interactions. CB[7], with its larger and more flexible cavity, consistently supports inclusion for all bipyridine isomers, regardless of charge state. These findings emphasize the importance of charge localization, host flexibility, and phase-specific effects in supramolecular assembly, which may further offer valuable insights for designing bipyridine- or bipyridinium-based materials.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1039/d5cp02677f | DOI Listing |
Top Curr Chem (Cham)
September 2025
Department of Organic Chemistry I, Faculty of Pharmacy and Lascaray Research Center, University of the Basque Country (UPV/EHU), Paseo de La Universidad 7, 01006, Vitoria-Gasteiz, Spain.
Aziridines, structurally related to epoxides, are among the most challenging and fascinating heterocycles in organic chemistry due to their increasing applications in asymmetric synthesis, medicinal chemistry, and materials science. These three-membered nitrogen-containing rings serve as key intermediates in the synthesis of chiral amines, complex molecules, and pharmaceutically relevant compounds. This review provides an overview of recent progress in catalytic asymmetric aziridination, focusing on novel methodologies, an analysis of the scope and limitations of each approach, and mechanistic insights.
View Article and Find Full Text PDFJTCVS Open
August 2025
Division of Cardiothoracic Surgery, Department of Surgery, University of Southern California, Los Angeles, Calif.
Objective: Patients with heterotaxy-associated congenital heart disease often require multiple operations, which may have a cumulative effect on their outcomes. This study aimed to define the cardiac surgical course in a large cohort and identify longitudinal risk factors for death/transplant.
Methods: All patients with heterotaxy-associated congenital heart disease who underwent cardiac surgery at one institution from 2005 to 2022 were retrospectively reviewed.
J Phys Chem A
September 2025
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
The gas-phase structures of dibenzo-24-crown-8 (DB24C8) and dinaphtho-24-crown-8 (DN24C8) complexes with divalent metal ions (Mg, Ca, Sr, Ba, Fe, Ni, and Zn) were investigated by cryogenic ion mobility-mass spectrometry (IM-MS) in combination with density functional theory calculations. Several complexes, particularly those of DN24C8, exhibited multiple coexisting conformers. DFT-optimized structures were classified based on the relative orientation of the two aromatic rings in the crown ether.
View Article and Find Full Text PDFChem Sci
September 2025
Department of Chemistry, University of Hawai'i at Manoa Honolulu HI 96822 USA
By connecting laboratory dynamics with cosmic observables, this work highlights the critical role of reactions between highly reactive species in shaping the molecular inventory of the interstellar medium and opens new windows into the spectroscopically elusive corners of astrochemical complexity. The gas phase formation of distinct CH isomers is explored through the bimolecular reaction of tricarbon (C, XΣ ) with the vinyl radical (CH, XA') at a collision energy of 44 ± 1 kJ mol employing the crossed molecular beam technique augmented by electronic structure and Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. This barrierless and exoergic reaction follows indirect dynamics and is initiated by the addition of tricarbon to the radical center of the vinyl radical forming a symmetric doublet collisional complex (CCCCHCH).
View Article and Find Full Text PDFInorg Chem
September 2025
Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
Neptunium exhibits truly unique chemistry as its speciation is dominated by the neptunyl(V) ion (NpO). Here, we describe the spontaneous destabilization and reduction of neptunyl(V) via complexation to the Keggin-type polyoxometalate (POM) ligand PWO. The POM-mediated reduction of NpO does not require any reducing agent and occurs within minutes, at room temperature, and in aqueous solution.
View Article and Find Full Text PDF